Female reproduction 1

• Female reproductive tract consists of

  • vagina
  • Cervix
  • Uterus
  • Oviduct
  • Ovary
  • fimbrae

  
• fimbrae function


  • encloses the ovary and catches the oocyte to pull into oviduct for fertilisation
• ovary functions

  • folliculogenesis
  • oogenesis
  • hormone production
• ovarian hormones


  • androgen ( androstendione ) - produced by theca cells
  • oestrogen - produced by granulosa cells
  • progesterone - produced by luteal cells
• hormone dependent cycle in ovary 


  • follicular phase occurs before oocyte release at ovulation.
  • luteal phase occurs after ovulation - produced corpus luteum.
• folliculogenesis steps - brief 


  • primordial follicle
  • becomes primary follicle
  • becomes secondary follicle and tertiary follicle
  • graafian follicle produced from one follicle. - removves oocyte for fertilisation. - ovulation
  • ovulation occurs
  • corpus luteum left- remaining outer matter of follicle
  • regresses into corpus Albicans .
  • can count number of cycles an animal has had by counting theses corpus albicans
• oestrogen function

  • induces secondary sexual characteristics
  • prepares uterus for sperm transport
  • stimulate growth and activity of mammary glands and endometrium - uterus lining- implantation preperation
  • regulate secretion of gonadotrophins - FSH and LH
• hypothalamic - pituitary - gonadal axis 


  • hypothalamus produces GnRH which acts on anterior pituitary
  • antierir pituitary secretes gonadotrophins LH an FSH onto ovary
  • depending on stage of cycle ovary prduces either oestrogen or progesterone
  • oestrogen production is just prior to ovulation and during, acts as a positive feedback mechanism to inc LH and FSH - induces ovulation
  • progesterone and oestrogen production - initial oestrogen production acts as negative feedback loop - control gonadotrophin release - reduces
• oestrogens 


  • 17- oestradiol
  • oestrone
• progesterone function


  • prepares uterus to receive embryo
  • maintains uterus to receive embryo
  • maintains uterus during pregnancy
  • stims growth of mammary glands but suppress milk secretion
  • regulates secretion of gonadotrophins - FSH, LH
  • if lost during pregnancy - abortion starts
• Common progesterone types 


  • 17a - hydroxy - progesterone
  • 20a - hydroxy - progesterone
• ovarian follicles 


  • follicle is the function unit of ovary
  • contains hormone producing cells - granulosa and theca cells
  • contains gamete - oocyte
  • female mammals are born with a fixed number of primordial follicles
  • infertility increases with age - number of follicles decrease
• follicle growth - folliculogenesis 


  • follicle growth is called folliculogenesis
  • occurs in the follicular phase of ovarian cycle
  • primordial follicle ( 1 primary oocyte and 1 layer of pre- granulosa cells) becomes primary follicle - (increased oocyte size and 1 layer of cuboidal granulosa cells)
  • granulosa will become oestrogen producing cells in response to FSH
  • zona pellucida separates oocyte from granulosa cells
  • granulosa cells have FSH receptors but are gonadotrophin - independent at this stage
  • not production oestrogen in primary follidle
• • folliculogenesis - secondary follicle
  • multiple layers of granulosa cells
  • oocyte fully grown
  • theca cells form and differentiate into - theca interna and theca externa
  • theca cells will go on to procure androgens in response to LH
  • vascularised theca layer starts to occur
  • gonadotropins LH and FSH can now access the follicle via the blood
• primary follicle diagram

  
• secondary follicle diagram

  
• folliculogenesis tertiary follicle


  • tertiary ( antral ) follicle
  • granulosa cells secrete fluid into follicle
  • antrum forms blood has also now vascularised follicle - gonadotrophins can access cells an pituitary
  • pituitary LH induces theca cells to become steroidogenic
  • produce androgen androstenedione
  • androstenedione acts as substrate for oestrogen synthesis by granulosa cells - oestrogen levels rise
  • pituitary FSH induces granulosa cell proliferation
  • further stimulates oestrogen production
• Tertiary antral follicle diagram

  
• Graafian follicle

  
• graafian follicle 


  • single follicle is selected to form a dominant mature follicle - the graffan follicle
  • due to competition for FSH
  • remaining follicles degenerate - follicle atresia